Good News, Bad News, and Really Bad News!

Quote;
It's not a big job to shim the roller bearings end play per this forum.

There is no need to shim the roller bearing. There is no way to control the end play of the layshaft and it does not need control as there is no thrust applied. If you were to shim it on the left side there is still no stop on the right side unless you call the end of the splines butting up against the end of the kick-shaft bushing a wear surface. The ball bearing does not really control the end play either. It has no snap ring to locate it on the shaft and the fit is not tight enough to keep it from ending up where-ever it stops. Nor is the ball bearing retained in the case. When the case is at operating temperature the bearing is barely if at all gripped by the housing. I am not sure who determined that the layshaft rollers need to be shimmed but it was not Norton. I have installed countless roller bearings on the layshaft and have never shimmed one yet. Jim

comnoz said:

Quote;
It's not a big job to shim the roller bearings end play per this forum.

There is no need to shim the roller bearing. There is no way to control the end play of the layshaft and it does not need control as there is no thrust applied. If you were to shim it on the left side there is still no stop on the right side unless you call the end of the splines butting up against the end of the kick-shaft bushing a wear surface. The ball bearing does not really control the end play either. It has no snap ring to locate it on the shaft and the fit is not tight enough to keep it from ending up where-ever it stops. Nor is the ball bearing retained in the case. When the case is at operating temperature the bearing is barely if at all gripped by the housing. I am not sure who determined that the layshaft rollers need to be shimmed but it was not Norton. I have installed countless roller bearings on the layshaft and have never shimmed one yet. Jim

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Fred from Old Britts says (underline is mine):
http://www.oldbritts.com/gearbox_a.html

When using the roller bearing (06-7710) for the layshaft, the layshaft is allowed to float, so the end play needs to be checked. You check the amount of end play by using a dial indicator as shown in the following picture. Zero end play will lock up the gears and too much end play will make for sloppy meshing between gears. I try to have around .005" to .010" end play. The end play will grow slightly when the gearbox heats up during riding, so the .005" is a good value to try to obtain.

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Now I would never want to tell Jim anything about how to put a Norton together, I just followed what Fred said. When I did my box I did shim it just in case. If it doesn't do any good at least I hope it doesn't do any harm.

If the kicker shaft is too far to the right it will increase the tendency for the bike to pop out of first gear , adding shims to the left end of the layshaft will not help as the gear still floats on the shaft. To help first gear you need to install a shim between the inner case and the kicker shaft to move the kicker shaft and first gear to the left . That gives deeper engagement with the sliding gear which is being located by the shift fork.
Jim

PS I am just trying to help with what I have learned and I certainly may be wrong. So I won't be offended if someone tells me I am full of shit. But we will then have to determine the right way.

I'm riding out to my folks house and pulling away from a stop sign I feel something brush my calf. Shift into second, wind on some throttle and the kickstart lever moves back. I had put the roller layshaft bearing in a few years ago and it was still in there when I looked this winter.

Are the roller (Norvil 'Superblend') really fit it and forget it, or do they go bad ? If it is not the bearing what could it be (I didn't shim it either).


Greg

comnoz said:

To help first gear you need to install a shim between the inner case and the kicker shaft to move the kicker shaft and first gear to the left . That gives deeper engagement with the sliding gear which is being located by the shift fork.
Jim

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That is the way Fred shims it.

ludwig said:

comnoz said:

I.. To help first gear you need to install a shim between the inner case and the kicker shaft to move the kicker shaft and first gear to the left ..

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Of course ! ..I always tought that this was self evident ..

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But they weren't shimmed from the factory with the roller bearings.

kommando said:

The cause of this issue coming to surface was the introduction of the 850, the gearing was taller plus the engine gave extra torque which increased the loading on the gearbox. That plus a batch of duff bearings from Portugal made it a epidemic. Mine was on a 850 MK2a and had the Portugese bearing, so its not just on the MK3's.

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Ditto. I have a MkIIa and my layshaft bearing went at 10K miles. It was the Portuguese bearing. Fortunately for me, the bearing cage gave out at about 10 mph and nothing dramatic happened other than a loud clunk. Kickstarter started dancing and dropping down about 1 minute before the clunk. I was even able to drive it home 8 miles without causing any damage.

swooshdave said:

But they weren't shimmed from the factory with the roller bearings.

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I think that's because rollers were never fitted from the factory. Rollers can't control endplay of the layshaft so need to be shimmed.

swooshdave said:

comnoz said:

To help first gear you need to install a shim between the inner case and the kicker shaft to move the kicker shaft and first gear to the left . That gives deeper engagement with the sliding gear which is being located by the shift fork.
Jim

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That is the way Fred shims it.

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That is the correct way to shim it. That needs to be done with a ball or roller bearing . The choice of the bearing will not affect the need for shimming here. Jim

comnoz said:

That is the correct way to shim it. That needs to be done with a ball or roller bearing . The choice of the bearing will not affect the need for shimming here. Jim

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But they didn't shim at the factory, correct?

No they didn't shim them at the factory. And many get along fine with no shim there. But if your bike wants to come out of first gear when you are driving away from a stop that will usually cure it. jim

God, my friggin head is swimming. I've had my first commando for over a decade and been on several forums and email lists for nortons and I have never picked up on this bearing failure as a common issue after such a short period of miles. I have at least 20K miles on the bike since I bought it and I have no idea if the tranny was rebuilt before I bought it. So potentially this trnny has 30+ thousand miles on it and no real issues other than occasionally not wanting to shift properly. I am definitely going to have to rethink my trip to barber and how I get there.

britbike220 said:

... I am definitely going to have to rethink my trip to barber and how I get there.

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Just go and have a good time. God knows that you could have a flat, the rear axle could snap, the ground wire could break off your Boyer, etc. There are a thousand ways for the bike to break down. If you thought about all of them you would never get out of the yard.

With 30,000 miles on the bike the layshaft bearing probabaly has been changed. If you are really worried, change the bearing. If you worked at it steady you could have it done in half a day (the second time you did it). Plan on a whole day.

Greg

Welcome to the motor sports hobby world, especially obsolete British and in particular the Commando. Its a hobby that tests your mettle as a man in any way measured. I've been so many times up 4-5 am to repair/replace some item working fine right up till night leaving on a trip with friends. Barbers is a month away, plenty of time to suck out and re store a gear box if ya the cash on hand to get started this week. Thanks goodness it revealed its issue before far far away. I thank my lucky starts Trixie's rod bolt let got on my work commute and not in another state 140 miles away the night prior. That was after the 1st deer did Trix and me in, so did 80-85 where possible to feel more secure.

Just know took me about a decade to get familiar with Combats, I expect another dozen years picking up more shop gems like this kicker shim I've not had to do, so far.

If you have not spent a season or 3 reading everything in Cap. Norton's site, you are missing out on whole bunch of history and people and solutions gone down long before our time with a Commando challenger. Creeping up on 4 decades past soon.

Its worth while to groove the sleeve gear bushes and stack 3 inline so they don't drift together leaving shaft less supported.

britbike220 said:

God, my friggin head is swimming. I've had my first commando for over a decade and been on several forums and email lists for nortons and I have never picked up on this bearing failure as a common issue after such a short period of miles. I have at least 20K miles on the bike since I bought it and I have no idea if the tranny was rebuilt before I bought it. So potentially this trnny has 30+ thousand miles on it and no real issues other than occasionally not wanting to shift properly. I am definitely going to have to rethink my trip to barber and how I get there.

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Approx. 600 miles each way? Heck, just go. If it hasn't failed yet...

Is there a link to the bearing replacement process. Just curious if you have to pull the primary and clutch off, or can you get the layshaft out with the mainshaft in there?

Hopefully you don't have to actually pull the tranny case out of the cradle.

lrutt said:

Is there a link to the bearing replacement process. Just curious if you have to pull the primary and clutch off, or can you get the layshaft out with the mainshaft in there?

Hopefully you don't have to actually pull the tranny case out of the cradle.

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There is an excellent article on gearbox rebuilding by Fred Eaton of Old Britts. Has great photos that have helped me a lot.

lrutt,
Les(LAB) on the forum has some excellent pics he helped me a few months back w/ same question.
Search using "layshaft".
But yes you can leave the primary side alone, trans in place in bike and remove layshaft w/ main undisturbed.
I know this will stir some contraversay as many will tell you while your are in there replace all bearing,bushes,seals
kick pawl etc...
I'm only replacing the layshaft bearing because of history of failing.
I'm also replacing the kicker pawl due to a possible fractured pawl.
Kicker slips a tooth here and there now and then.
If my gears are not chipped and the rest of the non problem bearings are sound I'm going to button it up and
continue my riding experience.
It has just shy of 10,000 miles on it, original miles.
I'm going at it w/ a heat gun 1st before I put a flame on the aluminum housing.
I'm doing a replacement ball bearing but again I don't plan on racing the death out of her.
I purchased an SKF 6203 c-3 for around $5.00. That's what is in there so I'm replacing it with modern same.
Ask away as you go we all did along the way.
Marshal

Yes, it can be done.

IMHO, you won't save time or labor that way. What you save in terms of primary removal you'll add back in terms of unwieldiness of dealing with the box and mainshaft in situ. BUT no reason not to try - you can always walk around to the other side of the bike and remove the primary at any stage.

Best of luck. THIS IS NOT DIFFICULT. Tedious, yes. Difficult, no. Rewarding, yes.

I like the fact it is still on the bike cause I can get my son to step on the rear brake when I break loose the main shaft nut.
Marshal